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Is Occasional Light Drinking During Pregnancy Harmful?

by Ernest L. Abel, Ph.D. and Robert J. Sokol, M.D.

In the last two decades more than 5,000 articles
have been published on the effects of alcohol during pregnancy.
One might assume we'd now have some consensus about the dangers
of occasional light drinking during pregnancy. Unfortunately, this
isn't so. Our own sober (no pun intended) conclusion, based on a
critical evaluation of the literature, is that there are no known
clinically important risks to the fetus from an occasional drink
during pregnancy (see below for our definition of "occasional"
and "light"). Here are our reasons.

1. Personal Experience

About two-thirds of all Americans drink to some extent. Our mothers
and your mothers are probably among these 66%. One of us is a Dean
of a Medical School (R.J.S.); the other is a Professor in Obstetrics
and Gynecology (E.L.A.). While we are both hairless on top and somewhat
funny-looking, we are both of normal size and stature, are both
slightly pudgy, do not suffer from any visible birth defects, and
though you may disagree with us, (for what are we arguing), we think
we are of normal intelligence.

In other words, we don't look or act as if we have suffered as
a result of our mothers' having had a drink or two during their
pregnancies. We have also peered carefully at the minds and bodies
of our children. While it's too soon to know for sure, none of them
seems to be any more funny looking than we are, none of them seems
to have suffered any loss of IQ points from the occasional drinks
our spouses may have taken, and our food bills reflect their overwhelming
commitment to eating.

Now it's your turn reader - do you or any of your children seem
to have suffered as a result of an occasional motherly drink? Do
you personally know of anyone that has?

2. Historical Evidence

When this country was on its way to nationhood, drinking was the
norm. Our founding fathers and mothers drank far more than we do
today. George Washington was a whiskey distiller, John Adams drank
a tankard of hard cider every morning, Thomas Jefferson invented
the presidential cocktail party. Historical information about drinking
by women is hard to come by, but in the early 1800's there were
an estimated "100,000 female drinkers" and many more "who
consumed from one-eighth to one-quarter of the nation's spirituous
liquor." We may be mistaken (because of the adverse effects
of our own in-utero alcohol exposure), but we don't believe that
the people who wrote our Constitution, Declaration of Independence,
our Bill of Rights and the other laws by which we live, lost any
IQ points by being exposed to more alcohol in-utero than we ourselves
were. ( In raising this argument, we are more than aware of Dr.
Johnson's percept concerning patriotism being the last refuge of
the scoundrel).

3. Lies, Damned Lies, and Statistics

Lies. There is no practical objective way of
knowing how much anyone drinks. We as researchers are therefore
forced to rely on what people admit to when they are asked how many
drinks they have a day, a week, a month, or something like this.
But, how much is in a "drink?" We assume one drink is
the same as another and each contains about 1/2 oz of alcohol. This
just shows how naive we are. A bartender may use a "shot"
glass but who else does? The amount of beverage actually consumed
in a drink can vary from one to twelve ounces. If you pour most
of your pint into a tall glass and I just pour a finger into mine,
we'll both say we've had only one drink. If you were asking questions
about income you wouldn't ask "how many times do you get paid
a month?", would you? You'd want to know not only how often
but how much someone gets paid. This would tell you a lot provided
a dollar has the same value for everyone. But suppose you had Canadians
and Americans in your study. Both might say they make $250 a week,
but these dollars have different values in terms of what they will
buy. Or suppose you asked Israelis and Britons how much they make.
If both say they make 250 "pounds," do they make the same?
Nuff said. You get the point.

Damned Lies. Simply asking someone who drinks
a lot about how much he/she drinks is naive. People who drinks a
lot don't like to admit it. They deny. Technically speaking, they
lie. Sometimes they lie a lot. Trust a used car salesman before
you trust what an alcoholic tells you about his or her drinking.

Self-reports of drinking during pregnancy are always suspect.
Relating the dangers of a given number of "drinks" per
day to a particular risk to the fetus based on this information
is sophomoric. Because of denial, actual alcohol intake is underreported
by the abusive drinker - the individual most likely to be at risk
for giving birth to a child with alcohol related birth defects.
The risk to the fetus of what might appear to be "2 drinks
a day" is undoubtedly the result of a much higher intake.

Statistics. Alcohol is but one of many possible
risk factors, such as social class, maternal illness, genetic susceptibility,
smoking, diet, past health history, pregnancy complications, use
of drugs and exposure to environmental pollutants. In epidemiology,
statistical techniques are used to try to "even out" as
many of these cofactors as possible. The goal is to match people
as closely as possible except for their alcohol use. If you are
going to do this carefully, you especially need to control for heredity.
Charles Dickens made this point cogently in Pickwick Papers when
he wrote about a meeting of "The Brick Lane Branch of the United
Grand Junction Temperance Association." One of the new members
was "Betsy Martin, widow, one child and one eye. Goes out charring
and washing by day; never had more than one eye, but knows her mother
drank bottled stout, and shouldn't wonder if that caused it."

Consider IQ scores. If you are studying the causes of subnormal
IQ, isn't is reasonable to start with parental IQ? Claire Ernhart
and her coworkers did this when they examined the effects of lead
in children. They found lead was associated with decreased scores
in cognitive and verbal tests but when parental IQ was incorporated
into the analysis, the relationship was no longer significant. No
studies in fetal alcohol research have bothered to include parental
IQ as a factor. In a recent study, Ann Streissguth and her coworkers
used parental education as a surrogate for IQ, the assumption being
the more years in school, the higher the IQ. She then matched subjects
on parental school years. Black children were included in the test
but race could not be considered in the regression analysis because
of the "relatively small number" of black children. If
these were so few, why were they included at all? This point would
be totally academic except for the fact that the only 2 children
with Fetal Alcohol Syndrome in the original Seattle study were both
born to the same woman who was black! Black race has also been found
to be a major factor in susceptibility to parental alcohol effects
and Streissguth et al. state in their conclusions that
" the important covariates have been taken into account before
claiming a teratogenic effect" when in fact, the covariate
for race was not.

For subjects who are mentally retarded using parental school education
might be reasonable. But the Streissguth et al. study dealt
with trivial differences in IQ scores of 4-year-old children-less
than 5 points. If you or I stay up too late at night, our IQ's would
probably slip by more than 5 points? If you want to control for
parental IQ - measure parental IQ.

What's In A Name?

Not only do we as researchers have to worry about obtaining reliable
drinking histories, we need to agree on definitions or criteria
for "moderate", "social", "light",
and "occasional " drinking. But we still have no consensus
in terminology. "Moderate" or "social" drinking
in one study can include women who are "heavy" drinkers
in another. Even the same research group may use these terms inconsistently.
For example, Streissguth and her coworkers defined 4 drinks a day
as "social" drinking in one study, 2 drinks a day as "heavy"
drinking in another, and "never more than 3-4" as "social"
in yet another.

Unrealistic labels have also been used by researchers describing
observations in animals. For example, Clarren and Bowden described
the amount of alcohol producing blood level of 200-300 mg% in non-human
primates as "moderate." Similarily, in their study of
alcohol's impact on craniofacial development in mice, Sulik et
al. administered dosages of alcohol producing peak BALs of
193-215 mg% and discussed these levels in terms of "social"
drinking. If these levels represent "moderate" or "social"
drinking, the people drinking this much probably do most of their
socializing in a stupor.

What then is an "occasional" or "social" drink?
We realize any specific amount is arbitrary. We are prepared to
be arbitrary. We suggest that a BAL of less than 0.04% is compatible
with "social" drinking. This is equivalent to 2 drinks
(containing 1 oz. absolute alcohol) consumed over a 2 hour period
for someone weighing 140 lb. We know of no evidence to suggest that
this amount consumed occasionally, e.g., once or twice a week, will
cause bad things to happen to unborn babies.

What about studies that say spontaneous abortion rates are increased
about twofold for women drinking 1-2 drinks per day or less during
pregnancy, you say? We say the increased risk in these studies is
almost certainly due to the heaviest drinkers who only represent
a small proportion of the population - in other words, these studies
suffer from the "lies, damn lies and statistics" quandary.
In the Harlap et al. study the number of "heavy"
drinkers (more than 2 drinks/day) was reported as only 0.5% of the
study population. This is a lot less than the national median and
modal consumption for pregnant American women. Either the people
in this study are an unusual group (which raises other issues of
representativeness) or we're dealing with an instance of the "used
car salesman" syndrome - women in this study considerably underreported
their alcohol consumption. A reasonable interpretation is that the
risk for spontaneous abortion was present only among the 2-4% heaviest
exposed pregnancies.

Kline et al. retrospectively compared women who aborted
spontaneously with a control group and concluded that as little
as two drinks a week were a risk factor for spontaneous abortion.
While this study controlled for smoking, use of other drugs and
diet, it didn't control for social class since all women in this
study were on public assistance. When Kline repeated her study with
private patients the relation between drinking and spontaneous abortion
were no longer there.

Studies of abortion following alcohol exposure in nonhuman primates
are very, very consistent in finding that the blood alcohol threshold
level for spontaneous abortion is around 205 mg%. In dogs, the BAL
threshold is almost identical. These studies in non-human primates
and dogs are impressive in their consistency and in their support
for suspicion of underreporting in human studies.

How about lowered birth weight, one of the more reliably observed
effects associated with in utero alcohol exposure in humans and
animals?

In an often cited report, Little found that consumption of 2 drinks
per day produced a decrease in birth weight of 160 g. However, drinking
ranged from 0 to 5 drinks a day, and 3 of the mothers in this study
could have been classified as alcohol abusers. Only seven of the
801 children in the study weighed under 2500 g. Little did not indicate
the birth weights of the children born to the alcohol abusers or
the drinking behavior of the mothers of the low birth weight infants.
It's more than likely that the alcohol abusers accounted for most
of the relationship.

In another study alleging to show significant effects of "occasional"
drinking, Streissguth and her co-workers reported that eight-month-old
children had significantly poorer performances on the Bayley tests
after statistical adjustment for a number of confounding variables.
However, infants born to women drinking more than 8 drinks per day
were lumped in with those whose mothers drank 2 or more drinks per
day. When Hank Rosett reanalyzed these data by specific dose and
each infant was included only once, only the mental scores of the
infants exposed to the higher amounts were significant and their
average score was still a normal 98!

Sutton's Law

There is good reason to believe thresholds exist for various adverse
alcohol-related birth defects and it's reasonable for clinicians
to recommend abstinence to patients contemplating pregnancy or already
pregnant. Unfortunately, the patient who places her unborn offspring
at greatest risk, i.e., the abusive drinker or alcohol-dependent
woman, is the individual least willing or able to identify herself
as a risk drinker or to become abstinent.

When someone asked Willie Sutton why he robbed banks, he answered,
"That's where the money is..." The occasional or light
drinker is like the nickel in the cookie jar. The real loot, in
terms of preventing alcohol-related brain damage, isn't in the cookie
jar - it's in the vault, in among the risk drinkers. These are the
women we must identify and help to become abstinent. Willie had
the right idea? Go where the money is.

Dr. Ernest Abel is Professor of Obstetrics
and Gynecology in the School of Medicine at Wayne State University.

Dr. Robert Sokol is Dean of the School of
Medicine at the same institution. He is past president of the World
Association of Pediatric Medicine, is an internationally recognized
authority on birth defects, and a consultant to such organizations
as the National Institute on Alcohol Abuse and Alcoholism, the Center
for Disease control, and the National Institute of Health.